PROJECT SUMMARY How Father & Grandparent Household Transitions Impact Child Growth and Cognition Adult family members influence child development through a variety of mechanisms such as providing resources for children, interacting with them, and influencing family decision-making. Though much research has found negative effects of father absence on child development, the relative importance of the mechanisms has not been determined. Furthermore, grandparents can play a large role in their grandchildren?s lives and changes in family structure involving grandparents could similarly impact child development. I will be trained and mentored so I am able to engage in independent research that seeks to understand the impacts of fathers and grandparents on child development, even when these family members are non-coresident with the children, and to identify mechanisms that drive the results. Latin America is an ideal location for studying these associations because longitudinal data indicate young children experience a significant degree of transitions in household structure, including grandparent transitions: three-generational households are a cultural norm. Using longitudinal survey data from five Latin American countries, I will document household transitions experienced during childhood and test how these are associated with child development outcomes. I will also identify mediating factors between household transitions and child development outcomes. Since the surveys will not have variables for all hypothesized mediators (such as the details of non-coresident family members? interactions with the child) I will adapt and validate survey questions from other sources for mothers, fathers, and maternal grandmothers about those potential pathways. In 2019, Chile?s nationally representative Longitudinal Survey of Early Childhood will include these instruments. Questions for the mothers will be asked of all mothers, while a smaller phone survey will question fathers and grandmothers (both inside and outside the household). Using this new data, I will assess additional mediation pathways as to how household transitions influence child development. By extending the literature on household structure to transitions involving grandparents and by providing novel data on non-coresident family members, my research will measure the associations between household transitions and child development and provide evidence supporting which pathways are pertinent. To strengthen my research, I will be mentored and trained in the science and theory of child development. Additional mentorship and training in measurement and instrument design will provide me with essential tools for project evaluation. These new skills, combined with the research results highlighting potential mechanisms linking household transitions and child development, will prepare me to write an R01 grant that adapts and evaluates a program to help children through household transitions of fathers and grandparents in the Chilean context.